1. Field of the Invention
The present invention relates to a turning system for use in a track-laying vehicle and, more particularly, to a turning system for use in a track-laying vehicle such as a bulldozer, power shovel or crane which is most suitably applied to a turning system in which a steering motor driven by the rotation of a power source drives crawler belts provided at both sides of the vehicle such that a relative travel difference is caused between the crawler belts, thereby turning the vehicle rightwards or leftwards.
2. Description of the Prior Art
In a prior art turning system for the above-type track-laying vehicle, a target revolution speed for the steering motor is unitarily determined only by the displacement of a steering lever which is one form of a steering instructing means which can be displaced from a neutral position by operation and which instructs, according to the direction and distance of its displacement, a turning direction and a turning radius for the vehicle, the turning radius decreasing as the displacement distance increases.